As harmful elements propagated through the air such as fine dust, avian influenza, foot-and-mouth disease, MERS, mycobacteria, and the like cause serious problems, there has been a growing interest in eco-friendliness and increasing demand for a portable living environment measuring instrument. Therefore, there is a need for a high-sensitivity sensor.
In a typical semiconductor sensor, an electrode and a sensor material are formed in close contact with each other on a substrate and a heater is attached under the substrate to increase sensitivity. When the sensor material is in close contact with the electrode, there can be problems of increase in resistance and generation of leakage current. In addition, because of the need for the heater, there is a limit to reducing the size of the sensor, and a separate constant-voltage circuit breaker for preventing discharge is required due to overcurrent generated by the heater. Further, there is also a problem with a battery that operates such a system.
A separate embedded system for amplifying a current sensed by a sensory receptor, which is the sensor material, blocking leakage current, and converting signals is used to increase sensitivity. However, such a system has the disadvantage of amplifying noise.
Since such typical sensors are always accompanied by a problem of leakage current, there is a need for technology capable of preventing leakage current.
In sensory receptor-based electrochemical and photochemical sensors or biosensors, there are problems of deterioration in reliability and reduction in electrical sensitivity due to increase in contact resistance and generation of leakage current during conversion of measured currents into electrical signals.
Although sensor technology using graphene with high electron transfer speed has been applied, the problem of leakage current has not been solved. In order to apply the sensor technology, it is necessary to comprehensively consider detection limit, selectivity, and device.
Typical sensor technology has a problem in that it is impossible to measure particles having a size of 300 mm or less, only the concentration of mass can be measured, it is difficult to measure in real time, and sensor products are expensive. MEMS-based semiconductor sensors have low resolution due to the occurrence of minute leakage current and have lower sensitivity than photochemical sensors and thus are difficult to combine with IoT-based digital smart communication technology in view of low threshold voltage shift and mobility of transistors.
In addition, since ultra-fine dust real-time sensing technology using MEMS-based particle chips requires lots of processes such as dust collecting/filtering, ultrafine dust sorting and charging, ultrafine dust collecting, and conversion of water concentration through measurement of ultrafine dust current so as to increase sensitivity, there can be problem of deterioration in reliability.